Leeches are segmented worms that belong to the phylum Annelida and comprise the subclass Hirudinea. Leeches can be divided into two categories: non-blood-sucking leeches and blood-sucking leeches. Non-blood-sucking leeches are mainly snails and other mollusks that do not suck blood. Blood-sucking leeches living in the rice fields, ditches, rivers, ponds and lakes, and these leeches suck blood of vertebrates including human beings. To suck blood, leeches secrete hirudin, which is a traditional medicine for improving blood circulation.
Hirudin may be extract from medicinal leeches. Under conventional techniques, heads of leeches may be removed, crushed, and then homogenized to obtain a homogenized mixture. The homogenized mixture may be added various chemicals such as acetone mixture or saline solution. The new mixture may be then added additional chemicals to further extract hirudin. Because these techniques involve various chemicals, there is a safety concerns with respect to conditions that some of the harmful chemicals may not be able to be removed from the refined hirudin. Recently, a manual squeezing approach may be used to extract hirudin from leeches. While safer than chemical approaches, the approach not only generates less amount of hirudin but also causes damages on the leeches. These leeches may die and/or generate less amount of hirudin for the next hirudin extraction.